Correlations Between Changes of Absorption and Transformation of Light Energy by PSII in Pepper Leaves and the Variety Tolerance Under Low Temperature and Weak Light

【Objective】 The objective of this study is to explore the correlations between the changes of absorption and transformation of light energy by PSII in pepper leaves and the variety tolerance under low temperature and weak light,and to screen suitable indexes for evaluating chilling-and weak light-tolerance of pepper varieties.【Method】 The correlations between the changes of chlorophyll fluorescence parameters and the tolerance of 12 pepper varieties expressed as injury indexes under low temperature and weak light were studied by using modulated chlorophyll fluorescence techniques and correlation analysis.【Result】 After treated with low temperature(15℃/5℃,day/night) and weak light(100 μmol?m-2?s-1),the ΦPSⅡ(actual photochemical efficiency of PSⅡ),Fv′/Fm′(photochemical efficiency of open reaction centers of PSⅡ),qP(photochemical quenching),Fm′(maximal fluorescence in light-adapted state),Fo′(minimal fluorescence in light-adapted state) and Fv′(variable fluorescence in light-adapted state) in leaves of 12 pepper varieties decreased,NPQ(non-photochemical quenching) and Fs(steady-state fluorescence) increased,wherease the Fv/Fm changed little in leaves of 12 pepper varieties.Significant negative correlations between chilling injury indexes and ΦPSⅡ,Fv′/Fm′,qP,Fm′ or Fv′ were observed in 12 pepper variety leaves treated with low temperature and weak light for 15 days;wherease a significant positive correlation between chilling injury indexes and NPQ was observed in pepper leaves treated with low temperature and weak light conditions for 15 days.【Conclusion】 It was proposed that ΦPSⅡ,Fv′/Fm′,qP,NPQ,Fm′ and Fv′ in leaves of pepper treated with 15°C/5°C,100 μmol?m-2?s-1PFD for 15 days could be used as simple and convenient tools for identification and screening a large number of chilling and weak-light tolerant pepper varieties.Among these parameters,ΦPSⅡ and Fv′ were the most sensitive ones.